Beta-blockers for suspected or diagnosed acute myocardial infarction

Quality of life assessment in the first episode of acute coronary syndrome

Background

Assessment of health-related quality of life (HRQoL) is an important measure of a patient's recovery after an illness. However, HRQoL among acute coronary syndrome (ACS) survivors has not been extensively studied following cardiac management.

Aim

The purpose of this study was to assess the quality of life (QoL) among ACS patients who have undergone percutaneous coronary intervention (PCI).

Methods

This cohort study included 145 consecutive male ACS patients between March 2021 and May 2022. Of these patients, 138 (mean age 54.3 ± 10.7 years) completed the QoL assessment using the short form-12 (SF-12) health survey questionnaire. Seventy (51%) of them presented with ST-segment elevation myocardial infarction (STEMI), 18 (13%) had non-STEMI, 39 (28%) had evolved MI, and 11 (8%) had unstable angina. Recruited patients' QoL data were assessed at various time points post-PCI.

Results

At the end of the 12 months of follow-up, major clinical events (MCE) defined as death, sudden death, or re-acute myocardial infarction occurred in 54.9% of patients. Out of 7 MCE, four deaths and three re-AMIs had occurred. SF-12 physical component score was found to be significantly improved when compared to the mental component score, which seems to improve without reaching statistical significance over time. Among event-free ACS patients, we found a significant positive correlation between left ventricular ejection fraction and HRQoL.

Conclusion

Improvement in HRQoL (physical component) was seen among ACS patients post-PCI.

Relevance for Patients

QoL assessment outcomes should be considered in clinical settings, practice guidelines, and treatment modality post-PCI to improve QoL in post-ACS survivors.

Association of beta-blockers beyond 1 year after myocardial infarction and cardiovascular outcomes

OBJECTIVE

Beta-blockers (BB) are an established treatment following myocardial infarction (MI). However, there is uncertainty as to whether BB beyond the first year of MI have a role in patients without heart failure or left ventricular systolic dysfunction (LVSD).

METHODS

A nationwide cohort study was conducted including 43 618 patients with MI between 2005 and 2016 in the Swedish register for coronary heart disease. Follow-up started 1 year after hospitalisation (index date). Patients with heart failure or LVSD up until the index date were excluded. Patients were allocated into two groups according to BB treatment. Primary outcome was a composite of all-cause mortality, MI, unscheduled revascularisation and hospitalisation for heart failure. Outcomes were analysed using Cox and Fine-Grey regression models after inverse propensity score weighting.

RESULTS

Overall, 34 253 (78.5%) patients received BB and 9365 (21.5%) did not at the index date 1 year following MI. The median age was 64 years and 25.5% were female. In the intention-to-treat analysis, the unadjusted rate of primary outcome was lower among patients who received versus not received BB (3.8 vs 4.9 events/100 person-years) (HR 0.76; 95% CI 0.73 to 1.04). Following inverse propensity score weighting and multivariable adjustment, the risk of the primary outcome was not different according to BB treatment (HR 0.99; 95% CI 0.93 to 1.04). Similar findings were observed when censoring for BB discontinuation or treatment switch during follow-up.

CONCLUSION

Evidence from this nationwide cohort study suggests that BB treatment beyond 1 year of MI for patients without heart failure or LVSD was not associated with improved cardiovascular outcomes.

Ivabradine in patients with acute ST-elevation myocardial infarction: a meta-analysis of randomized controlled trials

BACKGROUND

Elevated resting heart rate (HR) predicts poor outcomes in patients with coronary artery disease. Ivabradine has been recommended as a second-line anti-anginal agent in chronic coronary syndrome, while there are no clear indications for acute ST-elevation myocardial infarction (STEMI).

RESULTS

We systematically searched PubMed, Medline, EMBASE, Clinical Trials.gov, and the Cochrane Central Register of Controlled Trials with search terms Ivabradine and Acute myocardial infarction. There are two study outcomes from this study: therapeutic and safety effects. Therapeutic effects include the efficacy of Ivabradine on HR, all-cause mortality, heart failure incidence, left ventricular function and remodeling. Safety effects include troponin levels and ischemic events (recurrent angina pectoris). A total of 6 RCTs was included and showed that Ivabradine was associated with greater resting HR reduction [MD - 5.40; 95%CI - 8.60, - 2.20], improvement of left ventricular ejection fraction [MD 2.98; 95%CI 0.44, 5.51], and left ventricular end systolic volume [MD - 3.81; 95%CI - 6.88, - 0.75]. However, Ivabradine had no impact on all-cause mortality [OR 0.76; 95%CI 0.35, 1.67], heart failure incidence [OR 0.61; 95%CI 0.21, 1.80], and recurrent angina pectoris [OR 0.71; 95%CI 0.50, 1.00].

CONCLUSIONS

Ivabradine is safe and effective for resting HR reduction in patients with STEMI; however, it has no significant influence on mortality. These results suggest that an elevated HR is only a marker of risk but not a modifiable determinant of outcomes in patients who have suffered an acute myocardial infarction.

Long-term Survival Rate Following Myocardial Infarction and the Effect of Discharge Medications on the Survival Rate

BACKGROUND

The evaluation of the risk factors associated with the long-term survival rate of patients with myocardial infarction (MI) and the effects of discharge medications can significantly help select the most effective strategies for improving treatment.

STUDY DESIGN

A retrospective cohort study.

METHODS

The participants of this retrospective cohort study were 21,181 patients who suffered from MI and were hospitalized in the cardiac care unit (CCU) of different public, private, and military hospitals in Iran from 20 March 2013 to 20 March 2014. Participants were followed up until February 2020 for any cardiovascular disease (CVD) mortality. To evaluate survival rate, the differences between groups, and the factors related to MI death, Kaplan-Meier, log-rank test, and Cox proportional-hazards model were used, respectively.

RESULTS

One, three, five, and seven-year survival rates of patients were 88%, 81%, 78%, and 74%, respectively. Regarding the interaction effect of prescribed medical drugs, the highest 7-year survival rate of 86% (95% CI: 72%, 93%) was related to people who consumed anticoagulants, aspirin, clopidogrel, beta blockers, angiotensin-converting enzymes (ACEs), and angiotensin II receptor antagonist simultaneously. Considering the effect of other variables, the consumption of anticoagulants was associated with a decrease in survival rate (HR=1.13 CI: 1.06, 1.19).

CONCLUSION

As evidenced by the results of this study, different combinations of prescribed medication drugs had protective effects on long-term mortality compared to the group without any drug. Nonetheless, according to the drugs in each combination therapy, this protective effect ranged from HR=0.27 to HR=0.89. It is recommended that further studies compare the long-term effects of different drug combinations and also consider adherence to treatment in evaluating the effects of these combinations.

CXCR1 and its downstream NF-κB inflammation signaling pathway as a key target of Guanxinning injection for myocardial ischemia/reperfusion injury

Guanxinning Injection (GXNI) is used clinically to treat cardiac injury, but its active components and mode of action remains unclear. Therefore, a myocardial ischemia/reperfusion injury (MIRI) model-based integrated strategy including function evaluation, RNA-seq analysis, molecular docking, and cellular thermal shift assay (CETSA) was employed to elucidate the effect and mechanism of GXNI and its main ingredient on cardiac injury. These results revealed that GXNI significantly improved cardiac dysfunction and myocardial injury in I/R mice. RNA-seq analysis clarified that CXCR1-mediated interleukin-8 pathway played a critical role in MIRI. Molecular docking screening identified danshensu (DSS) as the major active components of GXNI targeting CXCR1 protein, which was confirmed in an oxygen-glucose deprivation/reoxygenation-induced cardiomyocytes damage model showing that GXNI and DSS reduced the protein expression of CXCR1 and its downstream NF-κB, COX-2, ICAM-1 and VCAM-1. CETSA and isothermal dose-response fingerprint curves confirmed that DSS combined with CXCR1 in a dose-dependent manner. Furthermore, GXNI and DSS significantly decreased the expression levels of IL-6, IL-1β and TNF-α and the number of neutrophils in post I/R myocardial tissue. In conclusion, this study revealed that GXNI and its active components DSS exert inhibitory effects on inflammatory factor release and leukocyte infiltration to improve I/R-induced myocardial injury by down-regulating CXCR1-NF-κB-COX-2/ICAM-1/VCAM-1 pathway.

Peer-support interventions for women with cardiovascular disease: protocol for synthesising the literature using an evidence map

INTRODUCTION

The leading cause of death for women is cardiovascular disease (CVD), including ischaemic heart disease, stroke and heart failure. Previous literature suggests peer support interventions improve self-reported recovery, hope and empowerment in other patient populations, but the evidence for peer support interventions in women with CVD is unknown. The aim of this study is to describe peer support interventions for women with CVD using an evidence map. Specific objectives are to: (1) provide an overview of peer support interventions used in women with ischaemic heart disease, stroke and heart failure, (2) identify gaps in primary studies where new or better studies are needed and (3) describe knowledge gaps where complete systematic reviews are required.

METHODS AND ANALYSIS

We are building on previous experience and expertise in knowledge synthesis using methods described by the Evidence for Policy and Practice Information (EPPI) and the Coordinating Centre at the Institute of Education. Seven databases will be searched from inception: CINAHL, Embase, MEDLINE, APA PsycINFO, the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials, and Scopus. We will also conduct grey literature searches for registered clinical trials, dissertations and theses, and conference abstracts. Inclusion and exclusion criteria will be kept broad, and studies will be included if they discuss a peer support intervention and include women, independent of the research design. No date or language limits will be applied to the searches. Qualitative findings will be summarised narratively, and quantitative analyses will be performed using R.

ETHICS AND DISSEMINATION

The University of Toronto's Research Ethics Board granted approval on 28 April 2022 (Protocol #42608). Bubble plots (ie, weighted scatter plots), geographical heat/choropleth maps and infographics will be used to illustrate peer support intervention elements by category of CVD. Knowledge dissemination will include publication, presentation/public forums and social media.

The Clinical Efficacy of Tirofiban Combined with Ticagrelor and Aspirin in Treating Acute Myocardial Infarction by Percutaneous Coronary Intervention and Its Effect on Patients’ Cardiac Function

Objective. To explore the clinical efficacy of tirofiban combined with ticagrelor and aspirin in acute myocardial infarction treatment by percutaneous coronary intervention and its effect on patients’ cardiac function. Methods. We selected 102 patients with acute myocardial infarction who came to The First Hospital of LanZhou University for treatment from July 2018 to May 2021. On the basis of conventional treatment, patients were separated into a joint group (tirofiban combined with ticagrelor and aspirin) comprising 55 cases and a control group (conventional ticagrelor and aspirin dual treatment) involving 47 cases. Blood flow classification of the two groups of patients was immediately recorded and compared after the myocardial infarction thrombolysis test (TIMI). Left ventricular function-related indicators, platelet-related parameters, neutrophil/lymphocyte ratio (NLR), red blood cell distribution width (RDW), and platelet/lymphocyte ratio (PLR) before treatment and 7 days after PCI were evaluated and compared between the groups before treatment and 3 months after treatment. ELISA was utilized to detect the serum levels of inflammatory factors, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and hypersensitive C-reactive protein (hs-CRP) before and after treatment. Incidence of major adverse cardiovascular events (MACEs) and adverse reaction incidence was put into comparison between the two groups in the course of the 3-month follow-up period. Compared with the control group, the joint group accounted for more patients with TIMI blood flow classification level 3 ( $P<0.05$ ) and showed more drastic improvement on the left ventricular function, platelet-related parameters, and serum inflammatory factors ( $P<0.05$ ). Moreover, patients of the joint group suffered less fluctuation from RDW, NLR, and PLR ( $P<0.05$ ), and their incidence of MACE was drastically lower in contrast with the control group ( $P<0.05$ ). No notable changes were presented in terms of incidence of adverse reaction ( $P>0.05$ ). For patients who suffered from acute myocardial infarction and treated with percutaneous coronary intervention, the application of tirofiban combined with ticagrelor and aspirin could effectively reduce the incidence of no reflow or slow blood flow, improve myocardial perfusion function, and have marked curative effects. It is worthy of clinical promotion and application.

Death-Associated Protein Kinase 1 (DAPK1) Protects against Myocardial Injury Induced by Myocardial Infarction in Rats via Inhibition of Inflammation and Oxidative Stress

Objective

Heart failure and ventricular remodeling after acute myocardial infarction (AMI) are important factors affecting the prognosis of patients. Therefore, we expected to explore the therapeutic target of AMI by studying the effect of death-associated protein kinase 1 (DAPK1) on AMI rat model.

Materials and Methods

We used male Sprague-Dawley rats to make AMI model, and after 1, 3, 7, and 14 d, we detect the success rate of modeling and the expression change of DAPK1 through 2, 3, 5-triphenyl tetrazolium chloride staining, myocardial injury markers detection, echocardiographic detection, and histological experiment. In addition, we determined the effect of DAPK1 on AMI by subcutaneous injection of the DAPK1 inhibitor (TC-DAPK 6). The effect of DAPK1 on cardiomyocytes has also been verified in cell experiments on H9c2 cells.

Results

The expression of DAPK1 in AMI rats was significantly higher than that in sham group, and it increased with time. The expression of inflammatory factors (interleukin- (IL-) 1β, IL-6, and tumor necrosis factor-α) in AMI rats treated by TC-DAPK 6 was reduced. In addition, TC-DAPK 6 also reduced the activity of malonaldehyde and increased the activities of superoxide dismutase, glutathione, and catalase. The expression of antioxidant molecules such as peroxiredoxin1/4 and glutathione peroxidase1/3 was also promoted by TC-DAPK 6. In H9c2 cells, TC-DAPK 6 also reduced its oxidative stress level.

Conclusions

The increase of DAPK1 may be related to the pathogenesis of AMI. DAPK1 inhibitors protect cardiomyocytes from AMI-induced myocardial injury by reducing levels of inflammation and oxidative stress in myocardial tissue and cells.

Beta-blockers in patients without heart failure after myocardial infarction

BACKGROUND

Cardiovascular disease is the number one cause of death globally. According to the World Health Organization (WHO), 7.4 million people died from ischaemic heart disease in 2012, constituting 15% of all deaths. Beta-blockers are recommended and are often used in patients with heart failure after acute myocardial infarction. However, it is currently unclear whether beta-blockers should be used in patients without heart failure after acute myocardial infarction. Previous meta-analyses on the topic have shown conflicting results. No previous systematic review using Cochrane methods has assessed the effects of beta-blockers in patients without heart failure after acute myocardial infarction.

OBJECTIVES

To assess the benefits and harms of beta-blockers compared with placebo or no treatment in patients without heart failure and with left ventricular ejection fraction (LVEF) greater than 40% in the non-acute phase after myocardial infarction.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, Science Citation Index - Expanded, BIOSIS Citation Index, the WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, European Medicines Agency, Food and Drug Administration, Turning Research Into Practice, Google Scholar, and SciSearch from their inception to February 2021.

SELECTION CRITERIA

We included all randomised clinical trials assessing effects of beta-blockers versus control (placebo or no treatment) in patients without heart failure after myocardial infarction, irrespective of publication type and status, date, and language. We excluded trials randomising participants with diagnosed heart failure at the time of randomisation.

DATA COLLECTION AND ANALYSIS

We followed our published protocol, with a few changes made, and methodological recommendations provided by Cochrane and Jakobsen and colleagues. Two review authors independently extracted data. Our primary outcomes were all-cause mortality, serious adverse events, and major cardiovascular events (composite of cardiovascular mortality and non-fatal myocardial reinfarction). Our secondary outcomes were quality of life, angina, cardiovascular mortality, and myocardial infarction during follow-up. We assessed all outcomes at maximum follow-up. We systematically assessed risks of bias using seven bias domains and we assessed the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 25 trials randomising a total of 22,423 participants (mean age 56.9 years). All trials and outcomes were at high risk of bias. In all, 24 of 25 trials included a mixed group of participants with ST-elevation myocardial infarction and non-ST myocardial infarction, and no trials provided separate results for each type of infarction. One trial included participants with only ST-elevation myocardial infarction. All trials except one included participants younger than 75 years of age. Methods used to exclude heart failure were various and were likely insufficient. A total of 21 trials used placebo, and four trials used no intervention, as the comparator. All patients received usual care; 24 of 25 trials were from the pre-reperfusion era (published from 1974 to 1999), and only one trial was from the reperfusion era (published in 2018). The certainty of evidence was moderate to low for all outcomes. Our meta-analyses show that beta-blockers compared with placebo or no intervention probably reduce the risks of all-cause mortality (risk ratio (RR) 0.81, 97.5% confidence interval (CI) 0.73 to 0.90; I² = 15%; 22,085 participants, 21 trials; moderate-certainty evidence) and myocardial reinfarction (RR 0.76, 98% CI 0.69 to 0.88; I² = 0%; 19,606 participants, 19 trials; moderate-certainty evidence). Our meta-analyses show that beta-blockers compared with placebo or no intervention may reduce the risks of major cardiovascular events (RR 0.72, 97.5% CI 0.69 to 0.84; 14,994 participants, 15 trials; low-certainty evidence) and cardiovascular mortality (RR 0.73, 98% CI 0.68 to 0.85; I² = 47%; 21,763 participants, 19 trials; low-certainty evidence). Hence, evidence seems to suggest that beta-blockers versus placebo or no treatment may result in a minimum reduction of 10% in RR for risks of all-cause mortality, major cardiovascular events, cardiovascular mortality, and myocardial infarction. However, beta-blockers compared with placebo or no intervention may not affect the risk of angina (RR 1.04, 98% CI 0.93 to 1.13; I² = 0%; 7115 participants, 5 trials; low-certainty evidence). No trials provided data on serious adverse events according to good clinical practice from the International Committee for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH-GCP), nor on quality of life.

AUTHORS' CONCLUSIONS

Beta-blockers probably reduce the risks of all-cause mortality and myocardial reinfarction in patients younger than 75 years of age without heart failure following acute myocardial infarction. Beta-blockers may further reduce the risks of major cardiovascular events and cardiovascular mortality compared with placebo or no intervention in patients younger than 75 years of age without heart failure following acute myocardial infarction. These effects could, however, be driven by patients with unrecognised heart failure. The effects of beta-blockers on serious adverse events, angina, and quality of life are unclear due to sparse data or no data at all. All trials and outcomes were at high risk of bias, and incomplete outcome data bias alone could account for the effect seen when major cardiovascular events, angina, and myocardial infarction are assessed. The evidence in this review is of moderate to low certainty, and the true result may depart substantially from the results presented here. Future trials should particularly focus on patients 75 years of age and older, and on assessment of serious adverse events according to ICH-GCP and quality of life. Newer randomised clinical trials at low risk of bias and at low risk of random errors are needed if the benefits and harms of beta-blockers in contemporary patients without heart failure following acute myocardial infarction are to be assessed properly. Such trials ought to be designed according to the SPIRIT statement and reported according to the CONSORT statement.

Conceptual approach to developing quality measures for transgender patients

BACKGROUND

Valid and reliable quality measures can help catalyze improvements in health care. The care of transgender patients is ripe for quality measurement, as there is increasing awareness of the increasing prevalence of this population and the urgency of improving the health care they receive. While best practices may not exist for some aspects of transgender health care, other aspects are characterized by well-developed and highly evidence-based recommendations. Our objective was to create a list of potential quality measures for transgender care.

METHODS AND RESULTS

In consultation with our advisory panel, which consisted of clinical and academic experts in transgender medicine, we selected eight prominent clinical practice guidelines of transgender health care for review. Our four team investigators carefully reviewed all eight clinical practice guidelines. Through the course of multiple consensus-building meetings, we iteratively refined items until we had agreed upon a list of forty potential quality measures, all of which met the criteria for quality measures set forth in the Center for Medicare and Medicaid Services Blueprint for developing quality measures.

CONCLUSIONS

This manuscript explains the origin of the quality measures we developed, and also provides a useful roadmap to any group hoping to develop quality measures for a field that has not previously had any.

Study designs: Part 7 - Systematic reviews

In this series on research study designs, we have so far looked at different types of primary research designs which attempt to answer a specific question. In this segment, we discuss systematic review, which is a study design used to summarize the results of several primary research studies. Systematic reviews often also use meta-analysis, which is a statistical tool to mathematically collate the results of various research studies to obtain a pooled estimate of treatment effect; this will be discussed in the next article.

MiR-379 relieves myocardial injury after acute myocardial infarction by regulating tumor necrosis factor-α-induced protein 8

BACKGROUND

Acute myocardial infarction (AMI) is the myocardial avascular necrosis syndrome caused by coronary atherosclerotic plaque rupture, thrombosis or coronary artery occlusion. Therefore, it is of great significance to find new targets for the treatment of myocardial infarction. The purpose of this study was to investigate the effect of microRNA-379 (miR-379) on AMI and its mechanism.

METHODS

MiR-379 mimic was used to transfect H9c2 cells and we determined the protective effect of miR-379 on H9c2 by detecting the level of apoptosis. TargetScan software was used to detect miR-379's downstream targets. We constructed siRNA to analyze the effect of miR-379's downstream targets on H9c2 cells. In addition, we used miR-379 agomir to inject the tail vein of AMI rats to verify the effect of miR-379 on rat cardiomyocytes.

RESULTS

TargetScan detected that miR-379 and Tumor necrosis factor-α-induced protein 8 (TNFAIP8) may have binding sites and the dual luciferase reporter assay found that miR-379 binds to TNFAIP8 and inhibits its activity. MiR-379 mimic was found to reduce the expression of caspase3 and caspase9 in H9c2 cells and thereby reduce H2O2-induced cell damage. Inhibition of TNFAIP8 also significantly reduced apoptosis level and inhibited the NF-κB signaling pathway in H9c2 cells. Finally, miR-379 agomir was used to inject the tail vein of AMI rats and verified the protective effect of miR-379 in the heart in vivo.

CONCLUSIONS

MiR-379 has a binding site with TNFAIP8 and can inhibit its activity by binding to TNFAIP8 mRNA. SiRNA-TNFAIP8 can inhibit the NF-κB signaling pathway and protect myocardial cells from AMI-induced myocardial damage by reducing the apoptosis level of myocardial cells.

Beta-blockers for suspected or diagnosed acute myocardial infarction

BACKGROUND

Cardiovascular disease is the number one cause of death globally. According to the World Health Organization, 7.4 million people died from ischaemic heart diseases in 2012, constituting 15% of all deaths. Acute myocardial infarction is caused by blockage of the blood supplied to the heart muscle. Beta-blockers are often used in patients with acute myocardial infarction. Previous meta-analyses on the topic have shown conflicting results ranging from harms, neutral effects, to benefits. No previous systematic review using Cochrane methodology has assessed the effects of beta-blockers for acute myocardial infarction.

OBJECTIVES

To assess the benefits and harms of beta-blockers compared with placebo or no intervention in people with suspected or diagnosed acute myocardial infarction.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, Science Citation Index Expanded and BIOSIS Citation Index in June 2019. We also searched the WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, Turning Research into Practice, Google Scholar, SciSearch, and the reference lists of included trials and previous reviews in August 2019.

SELECTION CRITERIA

We included all randomised clinical trials assessing the effects of beta-blockers versus placebo or no intervention in people with suspected or diagnosed acute myocardial infarction. Trials were included irrespective of trial design, setting, blinding, publication status, publication year, language, and reporting of our outcomes.

DATA COLLECTION AND ANALYSIS

We followed the Cochrane methodological recommendations. Four review authors independently extracted data. Our primary outcomes were all-cause mortality, serious adverse events according to the International Conference on Harmonization - Good Clinical Practice (ICH-GCP), and major adverse cardiovascular events (composite of cardiovascular mortality and non-fatal myocardial infarction during follow-up). Our secondary outcomes were quality of life, angina, cardiovascular mortality, and myocardial infarction during follow-up. Our primary time point of interest was less than three months after randomisation. We also assessed the outcomes at maximum follow-up beyond three months. Due to risk of multiplicity, we calculated a 97.5% confidence interval (CI) for the primary outcomes and a 98% CI for the secondary outcomes. We assessed the risks of systematic errors through seven bias domains in accordance to the instructions given in the Cochrane Handbook. The quality of the body of evidence was assessed by GRADE.

MAIN RESULTS

We included 63 trials randomising a total of 85,550 participants (mean age 57.4 years). Only one trial was at low risk of bias. The remaining trials were at high risk of bias. The quality of the evidence according to GRADE ranged from very low to high. Fifty-six trials commenced beta-blockers during the acute phase of acute myocardial infarction and seven trials during the subacute phase. At our primary time point 'less than three months follow-up', meta-analysis showed that beta-blockers versus placebo or no intervention probably reduce the risk of a reinfarction during follow-up (risk ratio (RR) 0.82, 98% confidence interval (CI) 0.73 to 0.91; 67,562 participants; 18 trials; moderate-quality evidence) with an absolute risk reduction of 0.5% and a number needed to treat for an additional beneficial outcome (NNTB) of 196 participants. However, we found little or no effect of beta-blockers when assessing all-cause mortality (RR 0.94, 97.5% CI 0.90 to 1.00; 80,452 participants; 46 trials/47 comparisons; high-quality evidence) with an absolute risk reduction of 0.4% and cardiovascular mortality (RR 0.99, 95% CI 0.91 to 1.08; 45,852 participants; 1 trial; moderate-quality evidence) with an absolute risk reduction of 0.4%. Regarding angina, it is uncertain whether beta-blockers have a beneficial or harmful effect (RR 0.70, 98% CI 0.25 to 1.84; 98 participants; 3 trials; very low-quality evidence) with an absolute risk reduction of 7.1%. None of the trials specifically assessed nor reported serious adverse events according to ICH-GCP. Only two trials specifically assessed major adverse cardiovascular events, however, no major adverse cardiovascular events occurred in either trial. At maximum follow-up beyond three months, meta-analyses showed that beta-blockers versus placebo or no intervention probably reduce the risk of all-cause mortality (RR 0.93, 97.5% CI 0.86 to 0.99; 25,210 participants; 21 trials/22 comparisons; moderate-quality evidence) with an absolute risk reduction of 1.1% and a NNTB of 91 participants, and cardiovascular mortality (RR 0.90, 98% CI 0.83 to 0.98; 22,457 participants; 14 trials/15 comparisons; moderate-quality evidence) with an absolute risk reduction of 1.2% and a NNTB of 83 participants. However, it is uncertain whether beta-blockers have a beneficial or harmful effect when assessing major adverse cardiovascular events (RR 0.81, 97.5% CI 0.40 to 1.66; 475 participants; 4 trials; very low-quality evidence) with an absolute risk reduction of 1.7%; reinfarction (RR 0.89, 98% CI 0.75 to 1.08; 6825 participants; 14 trials; low-quality evidence) with an absolute risk reduction of 0.9%; and angina (RR 0.64, 98% CI 0.18 to 2.0; 844 participants; 2 trials; very low-quality evidence). None of the trials specifically assessed nor reported serious adverse events according to ICH-GCP. None of the trials assessed quality of life. We identified two ongoing randomised clinical trials investigating the effect of early administration of beta-blockers after percutaneous coronary intervention or thrombolysis to patients with an acute myocardial infarction and one ongoing trial investigating the effect of long-term beta-blocker therapy.

AUTHORS' CONCLUSIONS

Our present review indicates that beta-blockers for suspected or diagnosed acute myocardial infarction probably reduce the short-term risk of a reinfarction and the long-term risk of all-cause mortality and cardiovascular mortality. Nevertheless, it is most likely that beta-blockers have little or no effect on the short-term risk of all-cause mortality and cardiovascular mortality. Regarding all remaining outcomes (serious adverse events according to ICH-GCP, major adverse cardiovascular events (composite of cardiovascular mortality and non-fatal myocardial infarction during follow-up), the long-term risk of a reinfarction during follow-up, quality of life, and angina), further information is needed to confirm or reject the clinical effects of beta-blockers on these outcomes for people with or suspected of acute myocardial infarction.